/******************************************************
Mini-transaction buffer

(c) 1995 Innobase Oy

Created 11/26/1995 Heikki Tuuri
*******************************************************/

#include "mtr0mtr.h"

#ifdef UNIV_NONINL
#include "mtr0mtr.ic"
#endif

#include "buf0buf.h"
#include "page0types.h"
#include "mtr0log.h"
#include "log0log.h"

/*******************************************************************
Starts a mini-transaction and creates a mini-transaction handle
and buffer in the memory buffer given by the caller. */

mtr_t *mtr_start_noninline(
    /*================*/
    /* out: mtr buffer which also acts as
    the mtr handle */
    mtr_t *mtr) /* in: memory buffer for the mtr buffer */
{
  return (mtr_start(mtr));
}

/*********************************************************************
Releases the item in the slot given. */
UNIV_INLINE
void mtr_memo_slot_release(
    /*==================*/
    mtr_t *mtr,            /* in: mtr */
    mtr_memo_slot_t *slot) /* in: memo slot */
{
  void *object;
  ulint type;

  ut_ad(mtr && slot);

  object = slot->object;
  type = slot->type;

  if (UNIV_LIKELY(object != NULL))
  {
    if (type <= MTR_MEMO_BUF_FIX)
    {
      buf_page_release((buf_block_t *)object, type, mtr);
    }
    else if (type == MTR_MEMO_S_LOCK)
    {
      rw_lock_s_unlock((rw_lock_t *)object);
#ifdef UNIV_DEBUG
    }
    else if (type == MTR_MEMO_X_LOCK)
    {
      rw_lock_x_unlock((rw_lock_t *)object);
    }
    else
    {
      ut_ad(type == MTR_MEMO_MODIFY);
      ut_ad(mtr_memo_contains(mtr, object, MTR_MEMO_PAGE_X_FIX));
#else
    }
    else
    {
      rw_lock_x_unlock((rw_lock_t *)object);
#endif
    }
  }

  slot->object = NULL;
}

/**************************************************************
Releases the mlocks and other objects stored in an mtr memo. They are released
in the order opposite to which they were pushed to the memo. NOTE! It is
essential that the x-rw-lock on a modified buffer page is not released before
buf_page_note_modification is called for that page! Otherwise, some thread
might race to modify it, and the flush list sort order on lsn would be
destroyed. */
UNIV_INLINE
void mtr_memo_pop_all(
    /*=============*/
    mtr_t *mtr) /* in: mtr */
{
  mtr_memo_slot_t *slot;
  dyn_array_t *memo;
  ulint offset;

  ut_ad(mtr);
  ut_ad(mtr->magic_n == MTR_MAGIC_N);
  ut_ad(mtr->state == MTR_COMMITTING); /* Currently only used in
                                                          commit */
  memo = &(mtr->memo);

  offset = dyn_array_get_data_size(memo);

  while (offset > 0)
  {
    offset -= sizeof(mtr_memo_slot_t);
    slot = dyn_array_get_element(memo, offset);

    mtr_memo_slot_release(mtr, slot);
  }
}

/****************************************************************
Writes the contents of a mini-transaction log, if any, to the database log. */
static void mtr_log_reserve_and_write(
    /*======================*/
    mtr_t *mtr) /* in: mtr */
{
  dyn_array_t *mlog;
  dyn_block_t *block;
  ulint data_size;
  ibool success;
  byte *first_data;

  ut_ad(mtr);

  mlog = &(mtr->log);

  first_data = dyn_block_get_data(mlog);

  if (mtr->n_log_recs > 1)
  {
    mlog_catenate_ulint(mtr, MLOG_MULTI_REC_END, MLOG_1BYTE);
  }
  else
  {
    *first_data = (byte)((ulint)*first_data | MLOG_SINGLE_REC_FLAG);
  }

  if (mlog->heap == NULL)
  {
    mtr->end_lsn = log_reserve_and_write_fast(first_data, dyn_block_get_used(mlog), &(mtr->start_lsn), &success);
    if (success)
    {
      return;
    }
  }

  data_size = dyn_array_get_data_size(mlog);

  /* Open the database log for log_write_low */
  mtr->start_lsn = log_reserve_and_open(data_size);

  if (mtr->log_mode == MTR_LOG_ALL)
  {
    block = mlog;

    while (block != NULL)
    {
      log_write_low(dyn_block_get_data(block), dyn_block_get_used(block));
      block = dyn_array_get_next_block(mlog, block);
    }
  }
  else
  {
    ut_ad(mtr->log_mode == MTR_LOG_NONE);
    /* Do nothing */
  }

  mtr->end_lsn = log_close();
}

/*******************************************************************
Commits a mini-transaction. */

void mtr_commit(
    /*=======*/
    mtr_t *mtr) /* in: mini-transaction */
{
  ut_ad(mtr);
  ut_ad(mtr->magic_n == MTR_MAGIC_N);
  ut_ad(mtr->state == MTR_ACTIVE);
#ifdef UNIV_DEBUG
  mtr->state = MTR_COMMITTING;
#endif
  if (mtr->modifications)
  {
    mtr_log_reserve_and_write(mtr);
  }

  /* We first update the modification info to buffer pages, and only
  after that release the log mutex: this guarantees that when the log
  mutex is free, all buffer pages contain an up-to-date info of their
  modifications. This fact is used in making a checkpoint when we look
  at the oldest modification of any page in the buffer pool. It is also
  required when we insert modified buffer pages in to the flush list
  which must be sorted on oldest_modification. */

  mtr_memo_pop_all(mtr);

  if (mtr->modifications)
  {
    log_release();
  }

#ifdef UNIV_DEBUG
  mtr->state = MTR_COMMITTED;
#endif
  dyn_array_free(&(mtr->memo));
  dyn_array_free(&(mtr->log));
}

/**************************************************************
Releases the latches stored in an mtr memo down to a savepoint.
NOTE! The mtr must not have made changes to buffer pages after the
savepoint, as these can be handled only by mtr_commit. */

void mtr_rollback_to_savepoint(
    /*======================*/
    mtr_t *mtr,      /* in: mtr */
    ulint savepoint) /* in: savepoint */
{
  mtr_memo_slot_t *slot;
  dyn_array_t *memo;
  ulint offset;

  ut_ad(mtr);
  ut_ad(mtr->magic_n == MTR_MAGIC_N);
  ut_ad(mtr->state == MTR_ACTIVE);

  memo = &(mtr->memo);

  offset = dyn_array_get_data_size(memo);
  ut_ad(offset >= savepoint);

  while (offset > savepoint)
  {
    offset -= sizeof(mtr_memo_slot_t);

    slot = dyn_array_get_element(memo, offset);

    ut_ad(slot->type != MTR_MEMO_MODIFY);
    mtr_memo_slot_release(mtr, slot);
  }
}

/*******************************************************
Releases an object in the memo stack. */

void mtr_memo_release(
    /*=============*/
    mtr_t *mtr,   /* in: mtr */
    void *object, /* in: object */
    ulint type)   /* in: object type: MTR_MEMO_S_LOCK, ... */
{
  mtr_memo_slot_t *slot;
  dyn_array_t *memo;
  ulint offset;

  ut_ad(mtr);
  ut_ad(mtr->magic_n == MTR_MAGIC_N);
  ut_ad(mtr->state == MTR_ACTIVE);

  memo = &(mtr->memo);

  offset = dyn_array_get_data_size(memo);

  while (offset > 0)
  {
    offset -= sizeof(mtr_memo_slot_t);

    slot = dyn_array_get_element(memo, offset);

    if ((object == slot->object) && (type == slot->type))
    {
      mtr_memo_slot_release(mtr, slot);

      break;
    }
  }
}

/************************************************************
Reads 1 - 4 bytes from a file page buffered in the buffer pool. */

ulint mtr_read_ulint(
    /*===========*/
    /* out: value read */
    byte *ptr,  /* in: pointer from where to read */
    ulint type, /* in: MLOG_1BYTE, MLOG_2BYTES, MLOG_4BYTES */
    mtr_t *mtr __attribute__((unused)))
/* in: mini-transaction handle */
{
  ut_ad(mtr->state == MTR_ACTIVE);
  ut_ad(mtr_memo_contains(mtr, buf_block_align(ptr), MTR_MEMO_PAGE_S_FIX) ||
        mtr_memo_contains(mtr, buf_block_align(ptr), MTR_MEMO_PAGE_X_FIX));
  if (type == MLOG_1BYTE)
  {
    return (mach_read_from_1(ptr));
  }
  else if (type == MLOG_2BYTES)
  {
    return (mach_read_from_2(ptr));
  }
  else
  {
    ut_ad(type == MLOG_4BYTES);
    return (mach_read_from_4(ptr));
  }
}

/************************************************************
Reads 8 bytes from a file page buffered in the buffer pool. */

dulint mtr_read_dulint(
    /*===========*/
    /* out: value read */
    byte *ptr, /* in: pointer from where to read */
    mtr_t *mtr __attribute__((unused)))
/* in: mini-transaction handle */
{
  ut_ad(mtr->state == MTR_ACTIVE);
  ut_ad(ptr && mtr);
  ut_ad(mtr_memo_contains(mtr, buf_block_align(ptr), MTR_MEMO_PAGE_S_FIX) ||
        mtr_memo_contains(mtr, buf_block_align(ptr), MTR_MEMO_PAGE_X_FIX));
  return (mach_read_from_8(ptr));
}

/*************************************************************
Prints info of an mtr handle. */

void mtr_print(
    /*======*/
    mtr_t *mtr) /* in: mtr */
{
  fprintf(stderr, "Mini-transaction handle: memo size %lu bytes log size %lu bytes\n",
          (ulong)dyn_array_get_data_size(&(mtr->memo)), (ulong)dyn_array_get_data_size(&(mtr->log)));
}
